Just for a moment - totally hypothetically - if one suspected that a
product such as Prevx was being offered by the 'bad guys' - are you
aware of any organisation which might be willing to look at same in
detail .............. just to rule it out, so to speak?

No. I'm reasonably sure that there are enough individuals doing so
that word would soon spread if anything untoward was found. A
cyber-friend of mine just loved to do things like that - not out of
suspicion, just out of curiosity - and publish his results. Since one
such disclosure got him in legal trouble, and labeled as a terrorist,
I'm not sure he publishes his findings anymore.

I bet he still does the reverse engineering for his own edification.

...it's sad really when the law helps the bad guys more than the
good guys.